Wafer transfer control apparatus and method for transferring wafer

ABSTRACT

The present invention provides a substrate transfer controlling apparatus which can easily maximize the throughput of a substrate processing apparatus such as a semiconductor fabrication apparatus, and can satisfy a demand for immediacy of actions of a transfer device. The substrate transfer controlling apparatus comprises an input device ( 12 ) for inputting times required for actions of transfer devices ( 1   a  through  1   c ) and times required to process substrates in processing devices ( 3   a  through  9   d ), and a schedule calculator ( 21 ) for calculating execution times of actions of the transfer devices ( 1   a  through  1   c ) for allowing the time when a final one of the substrates to be processed is fully processed and returned from the substrate processing apparatus to be earliest, based on a predetermined conditional formula including, as parameters, the inputted times. The substrate transfer controlling apparatus further comprises an action commander ( 24 ) for instructing the corresponding transfer devices to perform the actions at the calculated execution times of the actions of the transfer devices ( 1   a  through  1   c ).

TECHNICAL FIELD

The present invention relates to a substrate transfer controllingapparatus and a substrate transferring method, and more particularly toa substrate transfer controlling apparatus and a substrate transferringmethod for transferring a plurality of substrates in a substrateprocessing apparatus such as a semiconductor fabrication apparatus, witha transfer device, successively to a plurality of processing devices forprocessing the substrates therein. The present invention also relates toa substrate processing apparatus in which the transfer of substrates iscontrolled by such a substrate transfer controlling apparatus.

BACKGROUND ART

There are various types of configurations in semiconductor fabricationapparatus. Generally, there have been used many semiconductorfabrication apparatus which are arranged such that a plurality ofsemiconductor substrates (wafers) are successively introduced from acassette, and transferred between a plurality of processing devices by aplurality of transfer devices and processed concurrently thereby, andthe substrates that have been processed are returned to the cassette.There have been known other semiconductor fabrication apparatus in whicha plurality of cassettes can be mounted and replaced. Such semiconductorfabrication apparatus are continuously operable by replacing a cassetteloaded with processed substrates with a cassette loaded with unprocessedsubstrates. Operation of these semiconductor fabrication apparatus,particularly the transfer devices, is controlled by a substrate transfercontrolling apparatus.

A typical control process in a conventional substrate transfercontrolling apparatus will briefly be described below.

The conventional substrate transfer controlling apparatus iscontinuously supplied with the statuses of transfer devices which arebeing controlled thereby. Based on the supplied statuses of the transferdevices, the substrate transfer controlling apparatus detects anytransfer devices that are not in operation, i.e., any inoperativetransfer devices. If the substrate transfer controlling apparatusdetects any inoperative transfer devices, then it inspects, with respectto each of the inoperative transfer devices, whether there is aprocessed substrate in a processing device as a transfer source, whetherthere is an empty arm of the transfer device for receiving a substrate,and whether there is an empty processing device as a transferdestination. Then, the substrate transfer controlling apparatusdetermines all possible actions. Subsequently, with respect to each ofthe inoperative transfer devices where possible actions are present, thesubstrate transfer controlling apparatus determines an action to beperformed next, and transmits a command for carrying out the action tothe corresponding transfer device. In response to the received command,the inoperative transfer device starts the next action.

Specifically, if the substrate transfer controlling apparatus detectsthat the transfer device is inoperative at each point of time in theoperation of the semiconductor fabrication apparatus, then the substratetransfer controlling apparatus determines whether or not a condition forcarrying out a certain action to be done (operable condition) issatisfied. If there are any actions that satisfy the condition, then thesubstrate transfer controlling apparatus selects an action of highestpriority and instructs the transfer device to perform the selectedaction.

The substrate transfer controlling apparatus repeats the above processto control the transfer of substrates in the semiconductor fabricationapparatus.

With the conventional substrate transfer controlling apparatus, onlywhen the operable condition is satisfied, the inoperative transferdevice moves from the present position to the position of a processingdevice where a substrate is to be delivered or received. Specifically,even when the transfer device is inoperative, since it cannot movebefore the operable condition is satisfied, the throughput of thesemiconductor fabrication apparatus tends to decrease.

One solution is to modify the operable condition as much as possible toallow each transfer device to start moving early by predicting theprocessing end time in a processing device as a transfer source. Even ifthe operable condition is thus modified, since next actions aresuccessively determined, when a plurality of substrates are successivelyprocessed, the time for the final substrate to be returned to thecassette after it has fully been processed is liable to be later than alogically possible value (earliest time).

Furthermore, from the viewpoint of process, semiconductor fabricationapparatus are generally desired to transfer a substrate which has beenprocessed in a processing device promptly to a next processing device(the immediacy is required for the semiconductor fabrication apparatus).For example, when a substrate is plated, the plated substrate needs tobe transferred immediately to a next processing device andpost-processed for cleaning or the like because if the plated substratewere left as it is, it would be lowered in quality due to oxidization orthe like. Specifically, a certain constraint relative to the time tooperate a transfer device (in the above example, a condition that thewaiting time of a processed substrate for a transfer device is zero) maybe required.

However, in the conventional substrate transfer controlling apparatus,even if an operable condition with respect to an action of high priorityis satisfied, the transfer device cannot immediately perform the actionas long as the transfer device is in operation. Therefore, theconventional substrate transfer controlling apparatus cannot control thetransfer of substrates in consideration of constraints relative to thetime to operate a transfer device.

Consequently, it is necessary to conduct an advance simulation prior tooperation of the semiconductor fabrication apparatus to confirm whetherit is possible to perform a control process satisfying such aconstraint. However, such a process is tedious and time-consuming.Alternatively, it is necessary to pose a limitation on an expectedprocessing time for each type of processing device in order to satisfy aconstraint relative to the time to operate a transfer device. Further,the demand for immediacy of operation of the transfer device cannotaccordingly be met in some cases, thereby leading to a reduction inquality and yield. Alternatively, it is necessary to arrange apost-processing device which requires immediacy and a main processingdevice integrally with each other, thus resulting in a limitation on theapparatus arrangement.

DISCLOSURE OF INVENTION

The present invention has been made in view of the above conventionalproblems. It is an object of the present invention to provide asubstrate transfer controlling apparatus and a substrate transferringmethod which can easily maximize the throughput of a substrateprocessing apparatus such as a semiconductor fabrication apparatus, andcan satisfy a demand for immediacy of actions of a transfer device. Itis also an object of the present invention to provide a substrateprocessing apparatus which incorporates such a substrate transfercontrolling apparatus.

In order to solve the problems of the conventional substrate transfercontrolling apparatus, according to an aspect of the present invention,there is provided a substrate transferring method of transferringsubstrates with a transfer device between a plurality of processingdevices installed in a substrate processing apparatus, the substratetransferring method characterized by comprising: calculating executiontimes of actions of the transfer device for allowing the time when afinal one of the substrates to be processed is fully processed andreturned from the substrate processing apparatus to be earliest, basedon a predetermined conditional formula including, as parameters, timesrequired for the actions of the transfer device and times required toprocess the substrates in the processing devices; and instructing thecorresponding transfer device to perform the actions at the calculatedexecution times of the actions of the transfer device.

According to a preferred aspect of the present invention, in the abovemethod, the execution times of the actions of the transfer device arecalculated according to a linear programming process.

According to a preferred aspect of the present invention, the substratetransferring method further comprises: determining whether or not asolution of the execution times of the actions of the transfer device isobtained based on the conditional formula; and when it is determinedthat a solution of the execution times is not obtained, correcting theconditional formula so as to reduce the average number of substrateswhich are simultaneously present in the substrate processing apparatus,and retrying calculating the execution times based on the correctedconditional formula.

With the above method, since the execution times of actions of thetransfer device can be scheduled so that the time when a final one ofthe substrates to be processed is fully processed and returned from thesubstrate processing apparatus is made earliest, the throughput of thesubstrate processing apparatus can be maximized.

The time when a final one of the substrates to be processed is fullyprocessed and returned from the substrate processing apparatus can bemade earliest while satisfying constraints set in relation to the actiontimes of the transfer device without the need for an awkward advancereview and limitations on expected processing times. Therefore,requirements for the processing of substrates can be met, and thethroughput of the substrate processing apparatus can be maximized.

According to a preferred aspect of the present invention, the substratetransferring method further comprises: determining whether or not it isnecessary to newly calculate execution times of actions of the transferdevice after the substrate processing apparatus has started to operate;when it is determined that it is necessary to newly calculate executiontimes of actions of the transfer device, determining an assumed time anda final substrate to be processed in calculating the execution times;and while holding the result of a past scheduling process prior to thedetermined assumed time, calculating new execution times of actions forsubstrates up to the determined final substrate.

With the above method, even in a situation where the expected processingtimes of substrates while the substrate processing apparatus is incontinuous operation can sequentially be obtained in divided forms, thethroughput can approximately be maximized while satisfying limitationson the processing of substrates.

Because the number of additional substrates to be scheduled can bepresumed in view of a calculable number of substrates in each schedulingattempt, a computer of relatively low processing capability can performa scheduling process.

According to a preferred aspect of the present invention, the substratetransferring method further comprises: acquiring times when the transferdevice start the actions thereof; determining whether or not theacquired times and the execution times in the result of the pastscheduling process are inconsistent with each other or differ from eachother by at least a predetermined range; and when it is determined thatthe acquired times and the execution times in the result of the pastscheduling process are inconsistent with each other or differ from eachother by at least the predetermined range, correcting the executiontimes of the actions of the transfer device which are not performed atthat time.

With the above method, even if actions of a transfer device or theprocessing of substrates in processing devices is delayed behindexpected times, it is possible to minimize any effects of the delay onlimitations on the processing of substrates and the throughput, and thesubstrate processing apparatus can be operated without allowing sucheffects to remain in the future.

According to a preferred aspect of the present invention, the substratetransferring method further comprises: detecting a change in conditionswith respect to a substrate expected to be introduced into the substrateprocessing apparatus after the substrate processing apparatus hasstarted to operate; and when a change in conditions with respect to thesubstrate is detected, correcting the execution times of the actions ofthe transfer device on the substrate for which a condition is changedand substrates subsequent to the substrate for which a condition ischanged.

With the above method, even if there is a change in conditions withrespect to an unintroduced substrate, e.g., a cancellation of theprocessing of the substrate, a change in the expected processing time ofthe substrate, or a change in the sequence of introduction of thesubstrate into the substrate processing apparatus, the substrateprocessing apparatus can be operated flexibly based on the change in theconditions.

According to a preferred aspect of the present invention, in the abovemethod, when the process of at least one processing device in thesubstrate processing apparatus with respect to at least one substrate isomitted, the execution times of the actions of the transfer device arecalculated so as to transfer the at least one substrate to skip the atleast one processing device.

With the above method, since a substrate can be transferred to skip anunwanted processing device type or types while the substrate processingapparatus is being continuously operated, a plurality of processingdevice types can selectively be used depending on the purpose ofprocesses performed thereby. Therefore, the throughput of the substrateprocessing apparatus can greatly be increased, and the substrateprocessing apparatus can be operated flexibly for multi-productsmall-lot production.

According to another aspect of the present invention, there is provideda substrate transfer controlling apparatus for controlling transfer ofsubstrates with a transfer device between a plurality of processingdevices installed in a substrate processing apparatus, the substratetransfer controlling apparatus characterized by comprising: an inputdevice for inputting times required for actions of the transfer deviceand times required to process substrates in the processing devices; aschedule calculator for calculating execution times of actions of thetransfer device for allowing the time when a final one of the substratesto be processed is fully processed and returned from the substrateprocessing apparatus to be earliest, based on a predeterminedconditional formula including, as parameters, the times inputted withthe input device; and an action commander for instructing thecorresponding transfer device to perform the actions at the executiontimes of the actions of the transfer device which are calculated by theschedule calculator.

According to a preferred aspect of the present invention, in the aboveapparatus, the schedule calculator calculates the execution times of theactions of the transfer device according to a linear programmingprocess.

According to a preferred aspect of the present invention, the substratetransfer controlling apparatus further comprises: a solution judgingunit for determining whether or not a solution of the execution times ofthe actions of the transfer device is obtained by the schedulecalculator; and a retrying unit for, when it is determined by thesolution judging unit that a solution of the execution times is notobtained, correcting the conditional formula so as to reduce the averagenumber of substrates which are simultaneously present in the substrateprocessing apparatus, and retrying calculating the execution times bythe schedule calculator.

According to a preferred aspect of the present invention, the substratetransfer controlling apparatus further comprises: a schedule judgingunit for determining whether or not it is necessary to newly calculateexecution times of actions of the transfer device by the schedulecalculator after the substrate processing apparatus has started tooperate; and a calculating condition determiner for, when it isdetermined by the schedule judging unit that it is necessary to newlycalculate execution times of actions of the transfer device, determiningan assumed time and a final substrate to be processed in calculating theexecution times by the schedule calculator; wherein the schedulecalculator calculates new execution times of actions for substrates upto the final substrate determined by the calculating conditiondeterminer while holding the result of a past scheduling process priorto the assumed time determined by the calculating condition determiner.

According to a preferred aspect of the present invention, the substratetransfer controlling apparatus further comprises: an actual timeacquisition unit for acquiring times when the transfer device start theactions thereof; a rescheduling judging unit for determining whether ornot the times acquired by the actual time acquisition unit and theexecution times in the result of the past scheduling process areinconsistent with each other or differ from each other by at least apredetermined range; and a corrector for, when it is determined by therescheduling judging unit that the acquired times and the executiontimes in the result of the past scheduling process are inconsistent witheach other or differ from each other by at least the predeterminedrange, correcting the execution times of the actions of the transferdevice which are not performed at that time.

According to a preferred aspect of the present invention, the substratetransfer controlling apparatus further comprises: a condition changedetector for detecting a change in conditions with respect to asubstrate expected to be introduced into the substrate processingapparatus after the substrate processing apparatus has started tooperate; and a corrector for, when a change in conditions with respectto the substrate is detected by the condition change detector,correcting the execution times of the actions of the transfer device onthe substrate for which a condition is changed and substrates subsequentto the substrate for which a condition is changed.

According to a preferred aspect of the present invention, in the aboveapparatus, when the process of at least one processing device in thesubstrate processing apparatus with respect to at least one substrate isomitted, the schedule calculator calculates the execution times of theactions of the transfer device so as to transfer the at least onesubstrate to skip the at least one processing device.

According to still another aspect of the present invention, there isprovided a substrate processing apparatus having a plurality ofprocessing devices for processing substrates while transferring thesubstrates with a transfer device between the processing devices, thesubstrate processing apparatus characterized by comprising the abovesubstrate transfer controlling apparatus.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram showing an arrangement of a semiconductorfabrication apparatus according to an embodiment of the presentinvention;

FIG. 2 is a diagram showing an example of a hardware configuration ofthe substrate transfer controlling apparatus according to a firstembodiment of the present invention;

FIG. 3 is a block diagram showing a configuration of the substratetransfer controlling apparatus according to the first embodiment of thepresent invention;

FIG. 4 is a flowchart showing a substrate transfer controlling processaccording to the first embodiment of the present invention;

FIG. 5 is a block diagram showing a configuration of a substratetransfer controlling apparatus according to a second embodiment of thepresent invention;

FIG. 6 is a flowchart showing a substrate transfer controlling processaccording to the second embodiment of the present invention;

FIG. 7 is a diagram showing a visual representation of a time domain tobe scheduled according to the second embodiment of the presentinvention;

FIG. 8 is a block diagram showing a configuration of a substratetransfer controlling apparatus according to a third embodiment of thepresent invention;

FIG. 9 is a flowchart of a process carried out by a schedule correctorin the substrate transfer controlling apparatus according to the thirdembodiment of the present invention;

FIG. 10 is a block diagram showing a configuration of a substratetransfer controlling apparatus according to a fourth embodiment of thepresent invention;

FIG. 11 is a flowchart of a process carried out by a schedule correctorin the substrate transfer controlling apparatus according to the fourthembodiment of the present invention;

FIG. 12 is a diagram showing an example of an arrangement of a substrateprocessing apparatus;

FIG. 13 is a diagram showing an example of a flow of substrates betweenprocessing devices in the substrate processing apparatus shown in FIG.12;

FIGS. 14A and 14B are diagrams showing an order of substrates to bescheduled in FIG. 13;

FIG. 15 is a diagram showing an example of a flow of substrates betweenprocessing devices in the substrate processing apparatus shown in FIG.12;

FIGS. 16A and 16B are diagrams showing an order of substrates to bescheduled in FIG. 15;

FIG. 17 is a diagram showing an example of an arrangement of a substrateprocessing apparatus;

FIG. 18 is a diagram showing an example of a flow of substrates betweenprocessing devices in the substrate processing apparatus shown in FIG.17;

FIGS. 19A through 19C are diagrams showing an order of substrates to bescheduled in FIG. 18;

FIG. 20 is a block diagram showing an overall arrangement of a substrateprocessing apparatus incorporating a substrate transfer controllingapparatus according to the present invention;

FIG. 21 is a diagram showing the scheduled result obtained by schedulingexecution times of transfer devices with use of a substrate transfercontrolling apparatus according to the second embodiment of the presentinvention, immediately after the substrate transfer controllingapparatus has started to operate; and

FIG. 22 is a diagram showing the scheduled result obtained by schedulingexecution times of transfer devices with use of a substrate transfercontrolling apparatus according to the second embodiment of the presentinvention, after elapse of a certain time from the start of operation ofthe substrate transfer controlling apparatus.

BEST MODE FOR CARRYING OUT THE INVENTION

A substrate transfer controlling apparatus according to a firstembodiment of the present invention will be described below withreference to FIGS. 1 through 4. The substrate transfer controllingapparatus according to the present invention serves to control thetransfer of substrates between a plurality of processing devicesinstalled in a substrate processing apparatus. The substrate processingapparatus in which the transfer of substrates is controlled by thesubstrate transfer controlling apparatus will hereinafter be describedas a semiconductor fabrication apparatus for processing semiconductorsubstrates (wafers). However, the present invention is not limited tothe semiconductor fabrication apparatus, but is also applicable to asubstrate processing apparatus for processing glass substrates for LCDfabrication, for example.

FIG. 1 is a schematic diagram showing an arrangement of a semiconductorfabrication apparatus according to the present embodiment. As shown inFIG. 1, the semiconductor fabrication apparatus which is controlled bythe substrate transfer controlling apparatus according to the presentinvention comprises transfer devices 1 a through 1 c for transferringsubstrates, cassettes 2 a, 2 b which are loaded with substrates,temporary stages 3 a, 3 b for use in receiving and deliveringsubstrates, an inverter 4, water cleaning and drying devices 5 a, 5 b,chemical cleaning devices 6 a, 6 b, a rough cleaning device 7,preprocessing tanks 8 a, 8 b, and plating tanks 9 a through 9 d. In thepresent embodiment, not only the processing components 5 a through 9 d,but also the temporary stages 3 a, 3 b and the inverter 4 are handled asprocessing devices. The semiconductor fabrication apparatus may bearranged as any of various apparatus such as a CVD apparatus forperforming film deposition and a polishing apparatus for polishingsubstrates, and the processing devices may comprise various devices inaccordance with the semiconductor fabrication apparatus.

A substrate loaded in the cassette 2 a or 2 b is introduced into thesemiconductor fabrication apparatus by the transfer device 1 a,transferred to the temporary stage 3 a by the transfer device 1 a, andfurther transferred to the temporary stage 3 b by the transfer device 1b. Then, the substrate is transferred to the preprocessing tank 8 a or 8b by the transfer device 1 c, processed therein, and then reversed.Thereafter, the substrate is transferred to the plating tanks 9 athrough 9 d by the transfer device 1 c, processed therein, and furthertransferred to the rough cleaning device 7. After being roughly cleaned,the substrate is transferred to the chemical cleaning device 6 a or 6 bby the transfer device 1 b, processed thereby, further transferred tothe inverter 4, and reversed thereby. The substrate is finallytransferred to the water cleaning and drying device 5 a or 5 b by thetransfer device 1 a, processed thereby, and returned to the cassette 2 aor 2 b which was initially loaded with the substrate. Not only a singlesubstrate may be processed at a time, but also a set of a plurality ofsubstrates held together which are interconnected by a jig, for example,may be processed at a time.

In the present embodiment, the actions of the transfer devices 1 athrough 1 c are predefined. For example, predefined actions of thetransfer device 1 c include an action C for moving to the temporarystage 3 b and receiving a substrate therefrom, an action D fortransferring a substrate to the preprocessing tanks 8 a, 8 b anddelivering the substrate thereto, an action E for moving to thepreprocessing tanks 8 a, 8 b and receiving a preprocessed substratetherefrom, an action F for transferring a substrate to the plating tanks9 a through 9 d and delivering the substrate thereto, and an action Gfor moving to the plating tanks 9 a through 9 d, receiving a platedsubstrate therefrom, moving to the rough cleaning device, and deliveringthe substrate thereto.

The substrate transfer controlling apparatus in the present embodimentwill be described below. FIG. 2 is a diagram showing an example of ahardware configuration of the substrate transfer controlling apparatusaccording to the present embodiment, and FIG. 3 is a block diagramshowing a configuration of the substrate transfer controlling apparatusaccording to the present embodiment.

As shown in FIG. 2, the substrate transfer controlling apparatus 10comprises a central processing unit (CPU) 11, an input device 12 such asa pointing device including a keyboard, a mouse, and the like, and acommunication device for reading data stored in other computers, andstorage devices including a ROM 13, a memory 14, and a hard disk 15. Thesubstrate transfer controlling apparatus 10 is connected to the transferdevices 1 a through 1 c of the semiconductor fabrication apparatus viaan input/output interface 16. Signals from the CPU 11 are transmittedthrough the input/output interface 16 to the transfer devices 1 athrough 1 c of the semiconductor fabrication apparatus for therebycontrolling the transfer devices 1 a through 1 c.

The ROM 13 and the hard disk 15 store the codes of a computer programfor issuing commands to the CPU 11 or the like in cooperation with anoperating system (OS) to control the transfer of substrates. Thecomputer program is loaded into the memory 14 and executed incooperation with the CPU 11 for performing the following substratetransfer controlling process. The computer program in cooperation withthe CPU 11 provides, as shown in FIG. 3, a schedule calculator 21, asolution judging unit 22, a timetable generator 23, an action commander24, and a retrying unit 25. The hard disk 15 (or the memory 14) stores atimetable 17 generated (updated) by the timetable generator 23 describedlater.

A substrate transfer controlling process performed by the substratetransfer controlling apparatus 10 will be described below. FIG. 4 is aflowchart showing the substrate transfer controlling process performedby the substrate transfer controlling apparatus 10 according to thepresent embodiment.

Before the substrate processing apparatus starts to operate, timesrequired for actions of the transfer devices 1 a through 1 c in thesemiconductor fabrication apparatus (hereinafter referred to as“expected action times”) are inputted (Step 1). For example, an expectedtime required for the transfer devices 1 a through 1 c to receivesubstrates from processing devices, and an expected time required forthe transfer devices 1 a through 1 c to move from a processing device toanother processing device are inputted. The expected action times areinputted with the input device 12.

Times required for processing substrates in the processing devices 3 athrough 9 d (hereinafter referred to as “expected processing times”) areinputted (Step 2). For example, an expected time required to clean asubstrate in the rough cleaning device 7 is inputted. The expectedprocessing times are also inputted with the input device 12.

The input device for inputting the expected action times and theexpected processing times is not limited to a keyboard, a pointingdevice, and the like. For example, the expected action times and theexpected processing times may be prestored as a file in the storagedevice 14 or 15, and may then be inputted by reading the file.Alternatively, such a file may be saved in another computer, and theexpected action times and the expected processing times may be inputtedby reading the file through a communication device. For storing expectedaction times as a file, times actually required for the actions oftransfer devices may be measured by a computer connected to the transferdevices, and may be stored as expected action times in a file. In thiscase, by measuring times required for the actions of transfer deviceswhile the apparatus is being in operation, performing averaging or thelike, and then updating the expected action times stored in the file,the accuracy of expected action times can be increased, and theapparatus can cope with time-dependent changes thereof.

Next, the schedule calculator 21 derives action times of the actions ofthe transfer devices 1 a through 1 c (hereinafter referred to as“execution times”) for allowing the time when a final one of thesubstrates to be processed is fully processed and returned from thesemiconductor fabrication apparatus to be earliest (Step 3). Theschedule calculator 21 derives execution times by calculating a solutionsatisfying a certain conditional formula, and the details of thisprocess will be described later.

A solution satisfying the above certain conditional formula may notnecessarily be derived. After calculations carried out by the schedulecalculator 21, the solution judging unit 22 determines whether or not asolution satisfying the above certain conditional formula has beenobtained (Step 4).

If the solution judging unit 22 determines that a solution satisfyingthe above certain conditional formula has been obtained, then thetimetable generator 23 generates (updates) a timetable 17 based on theexecution times, i.e., a timetable in which the obtained execution timesare associated with the actions of the transfer devices that are to beperformed at the execution times, and stores the timetable 17 in thehard disk 15 (Step 5).

When the semiconductor fabrication apparatus is in operation, the actioncommander 24 controls the transfer devices 1 a through 1 c by referringto the timetable 17 stored in the hard disk 15. Specifically, the actioncommander 24 transmits a command for an action of the correspondingtransfer device through the input/output interface 16 to the transferdevice at an execution time described in the timetable 17. As a result,the time when a final one of the substrates to be processed is fullyprocessed and returned from the semiconductor fabrication apparatus ismade earliest. Before the action commander 24 transmits a command for anaction of each of the transfer devices 1 a through 1 c, the actioncommander 24 confirms that the transfer device is inoperative, and thatthe processing of a substrate in the processing device as a transfersource is completed, and that no preceding substrate is present in theprocessing device as a transfer destination and the resetting of theprocessing device is completed. If these conditions are not satisfied,then the action commander 24 waits until the conditions are satisfiedand thereafter transmits a command.

If the solution judging unit 22 determines that a solution satisfyingthe above certain conditional formula has not been obtained, then theretrying unit 25 corrects the conditional formula so as to reduce theaverage number of substrates which are simultaneously present on thetransfer devices and the processing devices in the apparatus, i.e., byadjusting intervals at which substrates are introduced, and retries theprocesses from Step 3 (Step 6). The conditional formula is corrected byinserting a virtual substrate (hereinafter referred to as “dummysubstrate”) for which the expected action times of the transfer devicesand the expected processing times of the processing devices are zero, ata suitable interval between substrates. At this time, if the number ofthe substrates that are simultaneously present in the apparatus isreduced, then the frequency of the actions of the transfer devices isreduced and hence the transfer devices can be operated more freely, sothat the probability that a solution will be obtained is increased. Ifno solution is obtained even after the retrying unit 25 retries theprocess, then the conditional formula is further corrected to reduce thenumber of the substrates which are simultaneously present in theapparatus. In extreme cases, after a preceding substrate is fullyprocessed and returned to the cassette 2 a or 2 b, a next substrate isintroduced into the apparatus.

Next, the setting of a conditional formula and the deriving of theexecution times in the schedule calculator 21 will be described belowwith a specific example. The setting of a conditional formula and thederiving of the execution times which will be described below areexamples thereof, and can be performed according to any of all otherprocesses.

First, the numbers (action numbers) k of actions of the transfer devices1 a through 1 c are defined successively as 1, 2, 3, . . . , K along apath from the introduction of a substrate into the semiconductorfabrication apparatus to the return of the substrate from thesemiconductor fabrication apparatus. It is assumed that a sufficienttime has elapsed from the start of operation of the semiconductorfabrication apparatus and the semiconductor fabrication apparatus is insteady operation with a sufficient number of substrates present therein,and the number of a next action to be executed by a transfer deviceperforming an action k is represented by kp(k). It is also assumed thata suitable number of dummy substrates are present before the firstsubstrate at the start of operation of the semiconductor fabricationapparatus and after the final substrate at the end of operation of thesemiconductor fabrication apparatus, with the substrate number n beingdetermined in the order in which substrates including the dummysubstrates are introduced from the cassette 2 a or 2 b into thesemiconductor fabrication apparatus, and an increment in the substratenumber of substrates to be handled when the action k changes to the nextaction kp(k) is represented by np(k). For example, with regard to thesemiconductor fabrication apparatus shown in FIG. 1, the actions aredefined as follows:

An action A of the transfer device 1 a to transfer a substrate loaded inthe cassette 2 a or 2 b to the temporary stage 3 a is defined as k=1, anaction B of the transfer device 1 b to transfer a substrate on thetemporary stage 3 a to the other temporary stage 3 b is defined as k=2,the action C of the transfer device 1 c to move to the temporary stage 3b and receive a substrate therefrom is defined as k=3, the action D ofthe transfer device 1 c to transfer the received substrate to thepreprocessing tank 8 a or 8 b and deliver the substrate thereto isdefined as k=4, the action E of the transfer device 1 c to move to thepreprocessing tank 8 a or 8 b and receive the substrate therefrom isdefined as k=5, the action F of the transfer device 1 c to transfer thereceived substrate to the plating tanks 9 a through 9 d and deliver thesubstrate thereto is defined as k=6, and the action G of the transferdevice 1 c to move to the plating tanks 9 a through 9 d, receive aplated substrate therefrom, move to the rough cleaning device 7, anddeliver the substrate thereto is defined as k=7.

On the assumption that a sufficient time has elapsed from the start ofoperation of the semiconductor fabrication apparatus and thesemiconductor fabrication apparatus is in steady operation with asufficient number of substrates present therein, a sequence of actionsof the transfer devices is determined. For example, a sequence ofactions of the transfer device 1 c is defined as a periodic sequence of3→5→4→6→7→3→ . . . in terms of the action numbers. In this example, nextactions are represented as follows:

kp(3)=5

kp(4)=6

kp(5)=4

kp(6)=7

kp(7)=3

The increments np in the substrate number when the action k changes tothe next action kp(k) are defined as shown below. The increments np aredetermined in view of the number of each type of the processing devices3 a through 9 d.

np(3)=−2

np(4)=−2

np(5)=+2

np(6)=−3

np(7)=+6

If each of substrates is assigned periodically in an introduced sequenceto the processing devices of the same type (e.g., 8 a and 8 b, 9 athrough 9 d), then expected action times are uniquely determined asshown below. These expected action times are inputted with the inputdevice 12 or calculated in view of the positions and paths of thetransfer devices based on the inputted values.

M1(k, n): Time for a transfer device to move prior to receiving asubstrate n from a position immediately before an action k

G1(k, n): Time for a transfer device to receive a substrate n from aprocessing device in an action k

M(k, n): Time for a transfer device to hold a substrate n and move in anaction k

G2(k, n): Time for a transfer device to deliver a substrate n to aprocessing device in action k

M2(k, n): Time for a transfer device to move after delivering asubstrate n in the action k

These expected action times may occasionally be zero.

The sum of the above expected action times is defined as Tg(k, n).Specifically,

Tg(k,n)=M1(k,n)+G1(k,n)+M(k,n)+G2(k,n)+M2(k,n)

The following non-negative variables are defined:

xr(k, n): Quiescent time of a transfer device immediately before anaction k on a substrate n

xw(k, n): Waiting time of a transfer device on a processing deviceimmediately before an action k on a substrate n

xf(k, n): Idle time of a processing device immediately before asubstrate is delivered to the processing device by an action k on asubstrate n

The waiting time xw(k, n) is defined only with respect to actionsincluding the reception of the substrate from the processing device. Theidle time xf(k, n) is defined only with respect to actions including thedelivery of the substrate to the processing device. Practically,however, the idle time xf(k, n) may be limited to actions to deliver thesubstrate to a relay-type processing device which is used to receive anddeliver substrates between transfer devices.

If the time to start an action k on a substrate n is represented by t(k,n), then the following three equations are established.

t(kp(k),n+np(k))=t(k,n)+Tg(k,n)+xr(kp(k),n+np(k))  (1)

t(k+1,n)=t(k,n)+Tg(k,n)−M2(k,n)+P(k,n)−M1(k+1,n)+xw(k+1,n)  (2)

t(k,n)=t(k+1,n−U(k))+M1(k+1,n−U(k))+G1(k+1,n−U(k))−M1(k,n)−G1(k,n)−M(k,n)+xf(k,n)  (3)

P(k, n) in the equation (2) represents an expected processing time ofthe substrate number n after an action indicated by the action number k,which is either inputted with the input device 12 or calculated based oninputted values. The expected processing time P(k, n) includes, inaddition to a time for plating, cleaning, or the like, which is normallyspecified for each of substrates, a time required for pre-actions suchas shutter closing and liquid filling performed before the substrate isprocessed by the processing device, and a time required for post-actionssuch as liquid removal and shutter opening performed after the substrateis processed by the processing device. U(k) in the equation (3)represents the number of processing devices of one type to which thesubstrate is delivered by the action k.

The equation (1) represents a time to start an action to be carried outby the same transfer device next after the action k on the substrate n.The equation (2) represents a time to start an action k+1 to be carriedout next after the substrate n is processed by the processing device.The equation (3) represents a time to start an action of the transferdevice to deliver the next substrate n after having received theprocessed substrate from the processing device.

The equations (1) through (3) can be modified as follows:

T=RmXr+Rv  (1a)

Xw=WmXr+Wv  (2a)

Xf=FmXr+Fv  (3a)

where T, Xr, Xw, Xf represent column vectors having t(k, n), xr(k, n),xw(k, n), xf(k, n) as respective elements, and Rm, Wm, Fm representsuitable matrixes, and Rv, Wv, Fv represent suitable column vectors.

The vector T on the left side of the equation (1a) contains an elementcorresponding to t(K, N) which represents a time to start an action toreturn the final substrate N (except for a dummy substrate). If acorresponding element in the vector Rm Xr on the right side of theequation (1a) is minimum, then the time when the final substrate to beprocessed is fully processed and returned from the semiconductorfabrication apparatus is made earliest.

The condition for allowing the time for returning substrates to beearliest can be expressed as follows:

cXr→minimum  (4)

where c represents a suitable row vector.

The conditions under which the transfer actions represented by the aboveequations (1a) through (3a) are physically established are normallyindicated by Xr≧0, Xw≧0, Xf≧0. From these inequalities and the aboveequations (1a) through (3a), there can be derived the followinginequalities:

Xr≧0  (1b)

WmXr≧−Wv  (2b)

FmXr≧−Fv  (3b)

If a certain time is required from the reception of a precedingsubstrate from a processing device by a transfer device until thedelivery of a next substrate to the processing device by a transferdevice, then the required time is added to the corresponding element onthe right side of the inequality (3b). For example, after the transferdevice 1 a receives a reversed substrate from the inverter 4, thetransfer device 1 b can deliver a next substrate to the inverter 4 onlywhen the reversing mechanism of the inverter 4 is reset. In this case, atime required to reset the reversing mechanism is added to thecorresponding element on the right side of the inequality (3b).

As indicated by the equation (1a), since all the times to start actionsare expressed by a linear expression of Xr, a linear constraint inrelation to an arbitrary action time can be expressed by a linearinequality relative to Xr. For example, if the constraint is such that asubstrate immediately after it has been processed is immediatelyreceived by an action k0, i.e., if xw(k0, n)=0, then the rowcorresponding to k0 in the equation (2a) is taken out and can beexpressed by the following linear inequality.

−Wm0Xr0≧Wv0  (5)

If a constraint is given to provide an upper limit for the time from thereception of a substrate n0 from an immediately prior processing devicein an action k0 until the delivery of the substrate n0 to a nextprocessing device in an action k0+1, then an inequality of a similarform can be derived. Similarly, it is possible to give a constraint toprovide a lower limit between times to start two actions, for therebyscheduling the transfer devices with a certain time allowance.Furthermore, it is also possible to define a waiting time from thedelivery of a substrate n to a processing device in an action k untilthe start of an actual process on the substrate n as xw(k, n), andformulate it so as to be included in the above variable vector Xr. Inthis case, the probability satisfying a constraint to provide an upperlimit for xw(k+1, n) can be increased.

The inequalities (1b) through (3b) and (5) can be expressed as follows:

AXr≧b  (6)

where A represents a suitable matrix and b represents a suitable columnvector.

Therefore, in order to allow the time to return the final substrate tobe earliest, it is necessary to determine a minimum value of theequation (4) under the inequality (6). Such a solution Xr can beobtained as a solution to a problem of a linear programming process.Once the solution Xr is obtained, the execution times of respectiveactions for allowing the time to return the final substrate to beearliest can be obtained from the equation (1a), and the above timetablecan be generated (updated) based on the obtained execution times.

A substrate transfer controlling apparatus according to a secondembodiment of the present invention will be described below withreference to FIGS. 5 through 7. FIG. 5 is a block diagram showing aconfiguration of the substrate transfer controlling apparatus 10according to the present embodiment, FIG. 6 is a flowchart showing asubstrate transfer controlling process carried out by the substratetransfer controlling apparatus 10 according to the present embodiment,and FIG. 7 is a diagram showing a visual representation of a time domainto be scheduled according to the present embodiment.

For operating a semiconductor fabrication apparatus continuously for along period of time, expected processing times for substrates may notnecessarily be predetermined, but expected processing times may bedetermined for unprocessed substrates in a cassette while thesemiconductor fabrication apparatus is in operation, e.g., each time anew cassette is loaded, and the transfer of the substrates may becontrolled based on those expected processing times. The substratetransfer controlling apparatus according to the second embodiment cancope with such a situation.

Specifically, the substrate transfer controlling apparatus 10 accordingto the present embodiment shifts a time domain to be scheduled as shownin FIG. 7 backward during operation of the semiconductor fabricationapparatus, repeats the scheduling successively, and joins the results ofrespective scheduling events consistently for controlling the transferof the substrates.

As shown in FIG. 5, the substrate transfer controlling apparatus 10according to the present embodiment has a calculation time table 18stored in the hard disk 15. A computer program stored in the storagedevices 13 through 15 in cooperation with the CPU 11 provides a schedulejudging unit 31, a calculating condition determiner 32, a schedulecalculator 33, a solution judging unit 34, a timetable generator 35, anaction commander 36, and a retrying unit 37.

A substrate transfer controlling process carried out by the substratetransfer controlling apparatus according to the present embodiment willbe described below.

As with the first embodiment, expected action times are inputted withthe input device 12 (Step 21), and expected processing times areinputted with the input device 12 (Step 22). In the second embodiment,data inputted with the input device are temporarily stored in thestorage device 14 or 15, and then read to enter expected action timesand expected processing times.

After the expected action times and the expected processing times areinputted, the schedule judging unit 31 determines whether or not a newscheduling process is required (Step 23), i.e., determines whether thereis a substrate that has not scheduled yet even though expectedprocessing times have been inputted.

If the schedule judging unit 31 judges that there is no substrate thathas not scheduled yet, i.e., no new scheduling process is required, thenthe process returns to Step 22 and waits for expected processing timesto be inputted.

If the schedule judging unit 31 judges that there is a substrate thathas not scheduled yet, then the calculating condition determiner 32determines an assumed time subsequent to the present time and a finalsubstrate (except for a dummy substrate) to be subject to schedulingcalculations (Step 24). The final substrate is a final one of newsubstrates to be subject to scheduling calculations, which are added tothe substrates which have already been scheduled, and is not a dummysubstrate.

The assumed time and the final substrate are determined as follows: Inthe results of a past scheduling process, as shown in FIG. 7, the timewhen a substrate including a dummy substrate is first returned to thecassette 2 a or 2 b after a final non-dummy substrate (which is not adummy substrate) has been introduced into the semiconductor fabricationapparatus is regarded as an assumed time. The number of additionalsubstrates in a range where scheduling calculations therefor can becompleted with an allowance from the present time to the assumed time ispresumed, and thus a final one of the additional substrates isdetermined. The number of additional substrates is presumed with therange of substrates which have not been scheduled yet but for whichexpected processing times have been inputted. If no positive number ofadditional substrates is obtained, then the assumed time is shifted tothe returning time of a next scheduled substrate, and the number ofadditional substrates is determined. In this manner, the interval fromthe assumed time to the time at which the final substrate is returnedrepresents an approximate time domain to be scheduled, as shown in FIG.7.

Here, the average value of times required to perform schedulingcalculations on added substrates is saved as the calculation time table18 in the hard disk 15. The calculating condition determiner 32estimates a suitable number of added substrates in view of the timesrequired for calculations which are saved in the calculation time table18.

The time to return the final substrate according to the new schedulingprocess is usually later than a true earliest value (earliest time)which is achieved when the expected processing times of all substratesare given in advance. If the number of substrates added in eachscheduling process is set to a relatively large value, then the time toreturn the final substrate according to the new scheduling process canbe approximated to the true earliest value.

After the calculating condition determiner 32 has determined an assumedtime and a final substrate to be subject to scheduling calculations, theschedule calculator 33 derives execution times of the actions of thetransfer devices within the above time domain to be scheduled based onthe conditional formula after the above additional substrates have beenadded (Step 25).

A lower limit for substrate numbers to be noticed for each action k isdetermined by referring to a set of action numbers of which executiontimes are subsequent to the assumed time and substrate numbers in theresults of the past scheduling process. Alternatively, a lower limit forsubstrate numbers may be determined by determining actions which canhappen subsequent to the assumed time due to the order of actions of thetransfer devices depending on expected processing times and expectedaction times. In this manner, the execution times of most actions priorto the assumed time are held, and the execution times of some actionsmay not be held in the vicinity of the assumed time, in the results ofthe past scheduling process.

Further, an upper limit for substrate numbers is determined bydetermining actions which can happen prior to the time to start thereturning action of the final substrate to be subject to the abovescheduling calculations to the cassette. It is assumed that dummysubstrates of which action times and processing times are zero existsubsequent to the final substrate.

Based on the lower limit and the upper limit thus determined forsubstrate numbers, unknown column vectors T, Xr, and the like areconstructed, and scheduling calculations are carried out. In each ofscheduling calculations, the average value of times required forscheduling calculations, which has been saved in the calculation timetable 18, is updated based on the times that are actually required forthe calculations.

When the semiconductor fabrication apparatus starts continuousoperation, the immediacy of scheduling is particularly important.Therefore, action times are determined in the order of actions k=1, 2, .. . , K as minimum values satisfying the equations (1) through (3) withrespect to the first substrate. If a single substrate is processed inthe semiconductor fabrication apparatus, then the action times thusdetermined allow the time to return the substrate to be earliest. Unlessexpected processing times and expected action times have extreme values,the substrate is processed by each of the processing devices 3 a through9 d and then immediately transferred to the next processing device bythe transfer devices 1 a through 1 c. Thus, an optimum solutionsatisfying the given constraint is determined.

After the schedule calculator 33 has performed its processing operation,as with the first embodiment, the solution judging unit 34 determineswhether or not a solution of execution times has been obtained (Step26). If a solution of execution times has been obtained, then thetimetable generator 35 generates (updates) a timetable (Step 27). Afterthe timetable has been generated (updated), the process returns to Step22, and the subsequent steps are repeated.

The action commander 36 refers to the timetable 17 stored in the harddisk 15 to control the transfer devices 1 a through 1 c, as with thefirst embodiment.

On the other hand, if the solution judging unit 34 judges that asolution of execution times has not been obtained, then the retryingunit 37 inserts a dummy substrate between substrates (Step 28), as withthe first embodiment. In this case, the calculating condition determiner32 determines an assumed time and a final substrate to be subject toscheduling calculations such that a non-dummy additional substrate willexist, also in view of the inserted dummy substrate.

In the present embodiment, since the execution times of actions of thetransfer devices which are determined by the new scheduling process maypossibly be prior to the assumed time, it is necessary to set a marginof safety to a large value in presuming the number of additionalsubstrates for finishing scheduling calculations earlier than theassumed time to allow the action commander 36 to issue action commandsto the transfer devices.

A substrate transfer controlling apparatus according to a thirdembodiment of the present invention will be described below withreference to FIGS. 8 and 9. FIG. 8 is a block diagram showing aconfiguration of the substrate transfer controlling apparatus 10according to the present embodiment.

As shown in FIG. 8, the substrate transfer controlling apparatus 10according to the third embodiment comprises a scheduler 40, a schedulecorrector 50, and an action commander 60, and has a progress data file19 stored in the hard disk 15. The action commander 60 corresponds tothe action commander 36 according to the second embodiment.

The scheduler 40 is constituted by the schedule judging unit, thecalculating condition determiner, the schedule calculator, the solutionjudging unit, the timetable generator, the action commander, and theretrying unit according to the second embodiment. The schedule corrector50 comprises an actual time acquisition unit 51, a rescheduling judgingunit 52, an invalidating unit 53, a progress data acquisition unit 54, acorrector 55, and a validating unit 56. The scheduler 40 and theschedule corrector 50 are provided by a computer program stored in thestorage devices 13 through 15 in cooperation with the CPU 11.

A substrate transfer controlling process carried out by the substratetransfer controlling apparatus according to the present embodiment willbe described below. FIG. 9 is a flowchart of a process carried out bythe schedule corrector 50 in the substrate transfer controllingapparatus according to the present embodiment.

The basic process carried out by the scheduler 40 is the same as theaforementioned process according to the second embodiment, but differstherefrom in that the conditional data including expected action timesand expected processing times, the times t(k, n), xr(k, n), and the dataof scheduling results such as the scheduled final substrate number andthe like are shared as the progress data file 19 with the schedulecorrector 50 and updated consistently.

Specifically, when the semiconductor fabrication apparatus startsoperation, expected action times of the individual transfer devices areinputted with the input device 12, and stored as the progress data file19 in the memory 14 or the hard disk 15. After the semiconductorfabrication apparatus starts continuous operation, when expectedprocessing times of each type of the processing devices for substratesare inputted with the input device 12, these expected processing timesare also stored as the progress data file 19 in the memory 14 or thehard disk 15. Thereafter, in order to reflect the execution times ofactions of the transfer devices as corrected by the schedule corrector50, the progress data file 19 is read, and the process is carried out upto the step of generating (updating) the timetable 17 with the timetablegenerator based on the progress data file 19. The results areaccumulated in the progress data file 19. The data accumulated in theprogress data file 19 which are old and unnecessary are successivelydeleted at respective times by referring to the numbers of substratesactually fully processed and returned to the cassette.

When the schedule judging unit is to determine whether new schedulingcalculations are necessary and when the calculating condition determineris to determine a final substrate, a limitation may be posed on therange of substrates to be subject to scheduling calculations in view ofthe storage capacity for the progress data file 19 and the frequency oftime corrections.

In the present embodiment, the schedule corrector 50 performs thefollowing process independently of the above process carried out by thescheduler 40.

The actual time acquisition unit 51 acquires times (hereinafter referredto as “actual times”) at which the transfer devices 1 a through 1 cactually start their actions, via the input/output interface 16 (Step41). Then, the rescheduling judging unit 52 determines the differencebetween the actual times acquired by the actual time acquisition unit 51and the execution times scheduled in the past and described in thetimetable 17, and determines whether or not the difference exceeds apredetermined allowable range (Step 42).

If the above delay time does not exceed the allowable range, then theactual time acquisition unit 51 acquires actual times again (Step 41).On the other hand, if the above delay time exceeds the allowable range,then the execution times described in the timetable 17 need to becorrected. Therefore, a process described below is performed (Steps 43through 47). The rescheduling judging unit 52 may determine whether ornot actions are inconsistent in relation to the actual times and theexecution times described in the timetable 17. For example, when anaction of a transfer device is delayed and another transfer device isscheduled to receive a substrate from a relay-type processing devicebefore the above transfer device actually delivers a substrate to therelay-type processing device, such actions are inconsistent, and hencethe execution times may be corrected.

When the actual time acquisition unit 51 is to acquire actual times, theactual time acquisition unit 51 may acquire, in addition to the timeswhen the transfer devices start to perform their actions, datarepresenting the progress of the actions, e.g., times to move toprocessing devices as transfer sources and transfer destinations, timesto end receiving and delivering substrates, and times to end processingin processing devices, for correcting execution times with higheraccuracy.

The Steps 43 through 47 are carried out as follows:

The invalidating unit 53 invalidates or stops the process of thescheduler 40 (Step 43), and the progress data acquisition unit 54acquires the progress data by referring to the progress data file 19(Step 44).

Then, the corrector 55 calculates new (corrected) execution times whichsatisfy the above equations (1) through (3), as minimum values notsmaller than the times scheduled in the past, for actions that are notperformed at present, with respect to substrates (including dummysubstrates) present on the transfer devices and the processing devicesin the semiconductor fabrication apparatus and a single first substrate(including a dummy substrate) to be introduced into the semiconductorfabrication apparatus, based on the progress data and the actual timesinputted by the actual time acquisition unit 51 (Step 45). At this time,the final substrate which has been scheduled is the single firstsubstrate to be introduced into the semiconductor fabrication apparatus,and a suitable number of dummy substrates are inserted subsequent to thefinal substrate for calculation purposes. The corrector 55 then updatesthe timetable 17 and the progress data file 19 based on the correctedexecution times (Step 46).

In calculating the above new execution times, for the sake of brevity,the times scheduled in the past may be shifted altogether back in timedrelation to a delay in the latest actual time. The time for a transferdevice to end receiving a substrate from a processing device as atransfer source or the time for a transfer device to end delivering asubstrate to a processing device as a transfer destination may becompared with the results of the past scheduling process.

Thereafter, the validating unit 56 validates or resumes the process ofthe scheduler 40 which has been invalidated or stopped by theinvalidating unit 53 (Step 47). After being validated or resumed, thescheduler 40 performs its process based on the updated data in theprogress data file 19.

If an action of a transfer device is delayed later than expected, theconstraint relative to the action times of the transfer device beingconsidered is not necessarily satisfied. Any deviation from theconstraint can be reduced to a negligible level by setting a delayreference in the rescheduling judging unit 52 to an appropriate value.After the process of the scheduler 40 has been validated or resumed, itis possible to determine an optimum value in the view of a constraintaccording to a linear programming process with respect to subsequentsubstrates, thus eliminating the effect of a time delay in the future.

A substrate transfer controlling apparatus according to a fourthembodiment of the present invention will be described below withreference to FIGS. 10 and 11. FIG. 10 is a block diagram showing aconfiguration of the substrate transfer controlling apparatus 10according to the present embodiment.

As shown in FIG. 10, the substrate transfer controlling apparatus 10according to the present embodiment comprises a scheduler 40, a schedulecorrector 70, and an action commander 60, and has a progress data file19 stored in the hard disk 15. The scheduler 40 and the schedulecorrector 70 are provided by a computer program stored in the storagedevices 13 through 15 in cooperation with the CPU 11. The schedulecorrector 70 in the present embodiment is constituted by a conditionchange detector 71, an invalidating unit 72, a progress data acquisitionunit 73, an expected processing time updater 74, a corrector 75, and avalidating unit 76.

The process performed by the scheduler 40 is the same as the processdescribed above in the second and third embodiments. The schedulecorrector 70 performs a process which is different from the processcarried out by the schedule corrector 50 according to the thirdembodiment. The process carried out by the schedule corrector 70 in thepresent invention will be described below. The process carried out bythe schedule corrector 70 is performed independently of the processperformed by the scheduler 40. FIG. 11 is a flowchart of the processcarried out by the schedule corrector 70 according to the presentembodiment.

After the semiconductor fabrication apparatus starts to operate, thecondition change detector 71 detects, through the input device 12,whether there is a change in conditions with respect to a substrate(hereinafter referred to as “unintroduced substrate”) expected to beintroduced into the semiconductor fabrication apparatus, e.g., acancellation of the introduction of an unintroduced substrate into thesemiconductor fabrication apparatus, a change in the expected processingtime of an unintroduced substrate, or a change in the sequence ofintroduction of an unintroduced substrate into the semiconductorfabrication apparatus (Step 51). If the condition change detector 71detects a change in conditions with respect to an unintroducedsubstrate, then since execution times described in the timetable 17 needto be corrected, the following process is carried out.

The invalidating unit 72 invalidates or stops the process of thescheduler 40 (Step 52), and the progress data acquisition unit 73acquires the progress data by referring to the progress data file 19(Step 53). The expected processing time updater 74 refers to a change inthe conditions with respect to an unintroduced substrate (a cancellationof the introduction of an unintroduced substrate into the semiconductorfabrication apparatus, a change in the expected processing time of anunintroduced substrate, or a change in the sequence of introduction ofan unintroduced substrate into the semiconductor fabrication apparatus),and updates the data regarding the expected processing times which hasbeen accumulated as part of the progress data (Step 54). For anunintroduced substrate which has been changed in conditions, a newintroducing sequence is established, and the expected processing timesare updated based on the new introducing sequence. If constraintsrelative to the transfer are specified for individual substrates, thenthese constraints are also updated.

If the first substrate for which expected processing times have beenupdated in Step 54 has already been scheduled in the past, then thecorrector 75 cancels the results of the scheduling process for thesubstrate and subsequent substrates among the results of the pastscheduling process in the progress data, and inserts a suitable numberof dummy substrates. Then, the corrector 75 calculates new (corrected)execution times which satisfy the above equations (1) through (3), asminimum values not smaller than the times scheduled in the past (Step55). At this time, the final substrate which has been scheduled is thefinal substrate for which expected processing times have not beenchanged in Step 54. The corrector 75 then updates the timetable 17 andthe progress data file 19 based on the corrected execution times (Step56). The time for a transfer device to end receiving a substrate from aprocessing device as a transfer source or the time for a transfer deviceto end delivering a substrate to a processing device as a transferdestination may be compared with the results of the past schedulingprocess.

Thereafter, the validating unit 76 validates or resumes the process ofthe scheduler 40 which has been invalidated or stopped by theinvalidating unit 72 (Step 57). After being validated or resumed, thescheduler 40 performs its process based on the updated data in theprogress data file 19. As a result, the execution times of actions onthe first substrate and subsequent substrates for which expectedprocessing times have been changed in Step 54 can be recalculated basedon the changed expected processing times. Even when a change occurs inthe conditions with respect to an unintroduced substrate, such as acancellation of the introduction of an unintroduced substrate into thesemiconductor fabrication apparatus, a change in the expected processingtime of an unintroduced substrate, or a change in the sequence ofintroduction of an unintroduced substrate into the semiconductorfabrication apparatus, the substrate processing apparatus can thus beoperated flexibly based on the change in the conditions.

The schedule corrector 70 according to the present embodiment and theschedule corrector 50 according to the third embodiment may be arrangedso as to function simultaneously with each other.

As described above, the schedule calculator in each of the aboveembodiments derives the execution times of actions of the transferdevices such that the time at which the final substrate has been fullyprocessed and returned from the semiconductor fabrication apparatus ismade earliest. According to the present invention, even if a certainsubstrate is instructed not to be processed by a certain processingdevice, it is possible to calculate the execution times of actions ofthe transfer devices to transfer the substrate so as to skip theprocessing device instructed not to process the substrate. The substratemay be instructed not to be processed by the processing device bysetting the expected processing time in the processing device for thesubstrate to zero.

For transferring the substrate to skip the processing device, a suitablenumber of dummy substrates are inserted immediately before theprocessing device to be skipped and also immediately prior to thesubstrate. The execution times are then calculated based on the abovelinear programming process on the assumption of the inserted dummysubstrates. By thus inserting a suitable number of dummy substrates, itis possible to transfer the substrate to skip the processing device.Insertion of such dummy substrates will be described below.

It is assumed that processing device types S1 through S3 are installedin a substrate processing apparatus, as shown in FIG. 12. It is alsoassumed that actions k−1, k, k+1 including the delivery of substrates tothe processing device types S1 through S3 are carried out by the sametransfer device, and that substrates A, B, C are introduced into andtransferred in and processed by the substrate processing apparatus inthe order named.

Here, a situation where the expected processing time of the substratesB, C with the processing device type S2 is set to zero, and hence thesubstrates B, C are transferred to skip the process in the processingdevice type S2 will be considered. FIGS. 13 and 15 show examples offlows of substrates between the processing device types shown in FIG.12, with the time axis being directed downwardly.

1) The transfer devices are operated in the order of k+1, k, k−1 duringsteady operation of the substrate processing apparatus, and the transferdevices are operated in the order of [k+1, 2], [k, 4], [k−1, 5], [k+1,3], [k, 5], and [k−1, 6] in terms of sets of action numbers andsubstrate numbers (FIG. 13).

In this case, as shown in FIG. 14A, a certain number of dummy substrateswhich correspond to the number of processing devices of the processingdevice type S2, i.e., two dummy substrates {circle around (2)}, {circlearound (3)} are inserted immediately prior to the substrate B. Theprocessing device type as a transfer source for the action [k+1, 2] onthe dummy substrate {circle around (2)} is changed from S2 to S1, andthe action [k+1, 2] is carried out prior to an action including thereception of the substrate B ({circle around (4)}) from the processingdevice type S1, i.e., prior to the action [k, 4] in the case of noskipping. As indicated by the dotted line in FIG. 13, the substrate B istransferred from the processing device type S1 to the processing devicetype S3. In this manner, the action [k+1, 2] does not obstruct theaction [k−1, 5] including the delivery of the substrate C ({circlearound (5)}) to the processing device type S1. The action [k, 4] ishandled as an action on a dummy substrate, i.e., an insubstantial actionof action time of zero.

Similarly, the processing device type as a transfer source for theaction [k+1, 3] on the dummy substrate {circle around (3)} is changedfrom S2 to S1, and the action [k+1, 3] is carried out prior to theaction [k, 5] including the reception of the substrate C ({circle around(5)}) from the processing device type S1, so as not to obstruct theaction [k−1, 6] including the delivery of the substrate D ({circlearound (6)}) to the processing device type S1. As indicated by thedotted line in FIG. 13, the substrate C is transferred from theprocessing device type S1 to the processing device type S3. The action[k, 5] is also handled as an insubstantial action.

When the above actions are performed, the dummy substrates which werepresent before the substrates B, C are moved backward of the substratesB, C after the action [k+1, 3], as shown in FIG. 14B.

2) The transfer devices are operated in the order of k, k+1, k−1 duringsteady operation of the substrate processing apparatus, and the transferdevices are operated in the order of [k, 3], [k+1, 2], [k−1, 4], [k, 4],[k+1, 3], [k−1, 5] in terms of sets of action numbers and substratenumbers (FIG. 15).

In this case, as shown in FIG. 16A, a certain number of dummy substrateswhich correspond to the number 2 of processing devices of the processingdevice type S2 minus 1, i.e., one dummy substrate {circle around (2)} isinserted immediately prior to the substrate B. The action [k, 3]including the reception of the substrate B ({circle around (3)}) fromthe processing device type S1 is handled as an action on the dummysubstrate, and the processing device type as a transfer source for anext action, i.e., the action [k+1, 2] on the dummy substrate {circlearound (2)}, is changed from S2 to S1. As a result, as indicated by thedotted line in FIG. 15, the substrate B is transferred from theprocessing device type S1 to the processing device type S3.

Similarly, the action [k, 4] including the reception of the substrate C({circle around (4)}) from the processing device type S1 is handled asan action on the dummy substrate, and the processing device type as atransfer source for the action [k+1, 3] on the dummy substrate {circlearound (3)} is changed from S2 to S1. As a result, as indicated by thedotted line in FIG. 15, the substrate C is transferred from theprocessing device type S1 to the processing device type S3.

In this manner, the reception of the substrate B from the processingdevice type S1 is completed before the action [k−1, 4] including thedelivery of the substrate C to the processing device type S1, and thereception of the substrate C from the processing device type S1 is alsocompleted before the action [k−1, 5] including the delivery of thesubstrate D to the processing device type S1. Therefore, the transferdevice can transfer these substrates C, D to the processing device typeS1 without problems. The dummy substrate which was present before thesubstrates B, C is moved backward of the substrates B, C after theaction [k+1, 3], as shown in FIG. 16B.

In the above description, one processing device type is skipped, and theaction k−1 is carried out by the same transfer device as the actions k,k+1. For transferring a substrate so as to skip a plurality ofprocessing device types, dummy substrates are inserted in view of allthose processing device types to be skipped to allow the substrate to betransferred while skipping those processing device types.

Even if the action k−1 is carried out by another transfer device, anaction of a transfer device for receiving a substrate from anddelivering a substrate to the other transfer device via a relay-typeprocessing device type is taken into consideration instead of the actionk−1, and the number of dummy substrates to be inserted is determined soas not to affect the action sequence of the other transfer device forthereby making it possible to skip the processing transfer device types.

Next, it is assumed that processing device types S1 through S4 areinstalled in a substrate processing apparatus, as shown in FIG. 17. Itis also assumed that actions k−1, k, k+1, k+2 including the delivery ofsubstrates to the processing device types S1 through S4 are carried outby the same transfer device, and that substrates A, B, C, D, E, F areintroduced into and transferred in and processed by the substrateprocessing apparatus in the order named. It is further assumed that theaction sequence of the transfer device is represented by k+2, k+1, k,k−1 during steady operation of the substrate processing apparatus, andthe actions of the transfer device are performed in the order shown inFIG. 18, with the time axis being directed downwardly in FIG. 18.

Here, a situation where the substrates C, D are transferred so as toskip the process in the processing device type S3 and the substrates E,F are transferred so as to skip the process in the processing devicetype S2 will be considered.

In this case, as shown in FIG. 19A, a certain number of dummy substrateswhich correspond to the number of processing devices of the processingdevice type S3, i.e., two dummy substrates {circle around (3)}, {circlearound (4)} are inserted immediately prior to the substrate C. Theprocessing device type as a transfer source for the action [k+2, 3] onthe dummy substrate {circle around (3)} is changed from S3 to S2, andthe action [k+2, 3] is carried out prior to the action [k+1, 5]including the reception of the substrate C ({circle around (5)}) fromthe processing device type S2. Thus, the substrate C is transferred soas to skip the processing device type S3.

Further, the processing device type as a transfer source for the action[k+1, 5] is changed from S2 to S1, and the action [k+1, 5] is carriedout prior to the action [k, 7] including the reception of the substrateE ({circle around (7)}) from the processing device type S1. Thus, thesubstrate E is transferred so as to skip the processing device type S2.At this time, one of the dummy substrates is moved backward of thesubstrate D, as shown in FIG. 19B.

Similarly, the processing device type as a transfer source for theaction [k+2, 4] is changed from S3 to S2, and the action [k+2, 4] iscarried out prior to the action [k+1, 6] including the reception of thesubstrate D from the processing device type S2. Thus, the substrate D istransferred so as to skip the processing device type S3.

Furthermore, the processing device type as a transfer source for theaction [k+1, 6] is changed from S2 to S1, and the action [k+1, 6] iscarried out prior to the action [k, 8] including the reception of thesubstrate F ({circle around (8)}) from the processing device type S1.Thus, the substrate F is transferred so as to skip the processing devicetype S2. At this time, the two dummy substrates are moved backward ofthe substrate F, as shown in FIG. 19C.

According to the present invention, since each of substrates can betransferred so as to skip an unwanted processing device type or typesand a plurality of processing device types can selectively be useddepending on the purpose of processes performed thereby while thesubstrate processing apparatus is being continuously operated, thesubstrate processing apparatus can flexibly be operated formulti-product small-lot production. For example, the throughput can bemade much greater than that in the case where the continuous operationis temporarily stopped and substrates to be processed differently arehandled. The cost can also be made much lower than that in the casewhere different substrate processing apparatuses are employed to servedifferent processing purposes.

When the schedule calculator (denoted by the reference numeral 21 inFIG. 3, the reference numeral 33 in FIG. 5) is arranged in view ofskipping processing device types, the corrector (denoted by thereference numeral 55 in FIG. 8, the reference numeral 75 in FIG. 10) isalso arranged in view of skipping processing device types.

A substrate processing apparatus incorporating a substrate transfercontrolling apparatus according to the present invention will bedescribed below with reference to the accompanying drawings. FIG. 20 isa block diagram showing an overall arrangement of a substrate processingapparatus (semiconductor fabrication apparatus) according to the presentembodiment. The substrate processing apparatus has the transfer devices1 a through 1 c, the cassettes 2 a, 2 b, and the processing devices 3 athrough 9 d shown in FIG. 1 as a main assembly. The substrate processingapparatus also has an apparatus controller 110 comprising a computer orthe like, a scheduler 102 comprising an independent computer or thelike, a display unit 104 for displaying statuses of the apparatus, andthe aforementioned input device 12 for inputting operating conditionsand control conditions of the apparatus.

Storage devices in the apparatus controller 100 and the scheduler 102store a computer program for controlling substrates and a computerprogram for controlling the apparatus. The apparatus controller 100 andthe scheduler 102 may be implemented by a plurality of computers incooperation with each other or a single computer.

The apparatus controller 100 mainly comprises controllers 110 through112 connected to the transfer devices 1 a through 1 c, the cassettes 2a, 2 b, and the processing devices 3 a through 9 d in the main assembly,and a main controller 120 connected to the controllers 110 through 112.The controllers 110 through 112 receive commands from the maincontroller 120 and transmit the commands to the devices 1 a through 9 d.The controllers 110 through 112 monitor the devices 1 a through 9 d andtransmit signals representative of the statuses of the devices 1 athrough 9 d to the main controller 20. The main controller 120 has afunction to transmit starting commands, processing conditions, and thelike to the processing devices 3 a through 9 d, and also includes anaction commander (denoted by the reference numeral 24 in FIG. 3, thereference numeral 36 in FIG. 5, the reference numeral 60 in FIGS. 8 and10), an actual time acquisition unit (denoted by the reference numeral51 in FIG. 8), a rescheduling judging unit (denoted by the referencenumeral 52 in FIG. 8), and a condition change detector (denoted by thereference numeral 71 in FIG. 10), all for controlling the transferdevices. The display unit 104 and the input device 12 are connected tothe main controller 120.

The scheduler 102 includes a schedule calculator (denoted by thereference numeral 21 in FIG. 3, the reference numeral 33 in FIG. 5), asolution judging unit (denoted by the reference numeral 22 in FIG. 3,the reference numeral 34 in FIG. 5), a retrying unit (denoted by thereference numeral 25 in FIG. 3, the reference numeral 37 in FIG. 5), atimetable generator (denoted by the reference numeral 23 in FIG. 3, thereference numeral 35 in FIG. 5), a schedule judging unit (denoted by thereference numeral 31 in FIG. 5), a calculating condition determiner(denoted by the reference numeral 32 in FIG. 5), an invalidating unit(denoted by the reference numeral 53 in FIG. 8, the reference numeral 72in FIG. 10), a progress data acquisition unit (denoted by the referencenumeral 54 in FIG. 8, the reference numeral 73 in FIG. 10), a corrector(denoted by the reference numeral 55 in FIG. 8, the reference numeral 75in FIG. 10), a validating unit (denoted by the reference numeral 56 inFIG. 8, the reference numeral 76 in FIG. 10), and an expected processingtime updater (denoted by the reference numeral 74 in FIG. 10).

The above arrangements of the main controller 120 and the scheduler 102are examples thereof, and the main controller 120 and the scheduler 102may of course be arranged differently.

Operation of the substrate processing apparatus incorporating thesubstrate transfer controlling apparatus will be described below.

The power supply of the main assembly is ganged with the power suppliesof the apparatus controller 100, the display unit 104, the input device12, and the scheduler 102. When the power supply of the main assembly isturned on, the power supplies of the apparatus controller 100, thedisplay unit 104, the input device 12, and the scheduler 102 areautomatically turned on, for thereby activating the apparatus controller100, the display unit 104, the input device 12, and the scheduler 102.At this time, the scheduler 102 is in a standby state waiting for asignal from the main controller 120.

Before the main assembly is operated, information as to whether theprocessing devices 3 a through 9 d are to be used or not, a transferringpath indicative of the sequence of transfer of substrates between thetypes of the processing devices 3 a through 9 d with the transferdevices 1 a through 1 c, and the sequence of basic actions of thetransfer devices 1 a through 1 c in steady operation of the substrateprocessing apparatus are inputted with the input device 12. The maincontroller 120 may transmit action commands to the transfer devices 1 athrough 1 c in the main assembly to operate the transfer devices 1 athrough 1 c, and acquire times required for the actions of the transferdevices 1 a through 1 c. If the acquired times and other settings arestored in a magnetic disk or a nonvolatile memory in the apparatuscontroller 100, then the substrate processing apparatus can be operatedbased on those acquired times and other settings even after the powersupply thereof is turned off.

When a starting command for operation of the apparatus is inputted withthe input device 12, the main controller 120 instructs the devices tostart their processing, i.e., to return the transfer devices 1 a through1 c to their home positions and initialize the processing devices 3 athrough 9 d, and also transmits an operation starting command and dataindicative of the transferring path, the sequence of basic actions, andexpected action times to the scheduler 102. The scheduler 102 readsthese data and performs an initializing process such as a settingprocess of its internal memory.

When the cassettes 2 a, 2 b loaded with unprocessed substrates aremounted in the main assembly, expected processing times for thoseunprocessed substrates and constraints about the transfer of theunprocessed substrates are inputted with the input device 12. Theseinputted data are transmitted via the main controller 120 to thescheduler 102.

The scheduler 102 reads the data of the expected processing times andthe constraints, generates a timetable by calculating execution times ofthe actions with respect to the first substrate according to the abovesubstrate transfer controlling process, and transmits the generatedtimetable to the main controller 120. Based on the timetable, the maincontroller 120 starts the actions of the transfer devices and theprocesses in the processing devices corresponding to the actions of thetransfer devices, and starts measuring the execution times of theactions. When transmitting action commands to the transfer devices 1 athrough 1 c, the main controller 120 confirms not only the passage oftimes indicated in the timetable, but also that the transfer devices areinoperative, the processing of substrates in processing devices astransfer sources has been completed, and preceding substrates are notpresent in processing devices as transfer destinations and the resettingof those processing devices has been completed. In this manner, noproblem occurs even if the action times of the transfer devices 1 athrough 1 c, the processing times of the processing devices 3 a through9 d, and the reset times deviate from expected times.

Simultaneously with transmitting the action commands, the maincontroller 120 transmits the execution times of the actions to thescheduler 120, and also transmits information about the positions of thesubstrates and the progress of the processes to the output device 104.Subsequently, these status data of the main assembly are continuouslytransmitted at suitable given intervals.

Then, the scheduler 102 sets a suitable number of additional substrateswith respect to the second and subsequent substrates for which expectedprocessing times have initially been acquired, successively schedulesthe substrates according to a linear programming process, and transmitsan updated timetable to the main controller 120. Prior to transmittingsuch an updated timetable, the scheduler 120 may transmit a command tostop the clock in the main controller 120 to inhibit new actions frombeing started, may transmit only commands corresponding to unperformedactions in the timetable, and then may restart the clock in the maincontroller 120 after transmitting those commands. In view of the storagecapacity of the storage devices in the main controller 120, thetimetable may be stored and accumulated in the storage devices in thescheduler 102, and a certain amount of schedule with unperformed actionsat first may periodically be transmitted sequentially to the maincontroller 120 irrespective of the timing of scheduling calculations.

When a cassette loaded with new unprocessed substrates is mounted in themain assembly, expected processing times and constraints of the transferthereof are inputted in the same manner as described above. The inputteddata are transmitted from the main controller 120 to the scheduler 102.The scheduler 102 reads these data, accumulates them in the progressdata file, and continues the above successive scheduling according tothe linear programming process.

When expected action times have been calculated with respect to allunintroduced substrates for which expected processing times have beeninputted, the scheduler 102 waits until the expected processing time ofa next unintroduced substrate is inputted.

While the main assembly is being in operation, the main controller 120measures the execution times of respective actions, and monitors anydifferences between the measured times and the times indicated in thetimetable. If the action times of the transfer devices 1 a through 1 c,the processing times of the processing devices 3 a through 9 d, and thereset times are delayed, then the execution time of a certain action maybe delayed as a result. In such a case, the rescheduling judging unit inthe main controller 120 transmits a time correction command to thescheduler 102, which corrects the execution time of the unperformedaction to update the timetable and transmits the updated timetable tothe main controller 120. The main controller 120 stops the clock beforetransmitting the time correction command, and restarts the clock afterhaving received the timetable, so that the corrected timetable andactual actions are consistent with each other.

When the mounted cassette loaded with unprocessed substrates is removedfrom the main assembly, or the expected introduction of unintroducedsubstrates is canceled, or the expected processing times thereof arechanged, or the sequence of introduction of unintroduced substrates intothe main assembly is changed with the input device 12, the informationindicative of the above event is transferred together with a correctioncommand for the unintroduced substrates from the main controller 120 tothe scheduler 102. The scheduler 102 updates a portion of the timetable,and transmits the updated timetable to the main controller 120. As inthe case of the time correction command, the main controller 120 stopsthe clock before a correction command for the unintroduced substrates istransmitted to the scheduler 102, and restarts the clock after havingreceived the timetable.

When all the substrates loaded in the cassette mounted in the mainassembly have been fully processed and returned to the cassette, themain controller 120 stops checking whether or not there is atransmission from the scheduler 102, performs an ending process such asa releasing process of the memory, and returns to the state subsequentto the activation. The scheduler 102 and the input device 12 also returnto the state subsequent to the activation. In this case, thetransferring path, the sequence of basic actions, and expected actiontimes for a next cycle of operation may be reset with the input device12. Alternatively, an operation starting command may be inputted againwith the same settings to resume the processing of substrates for acassette loaded with unprocessed substrates.

FIGS. 21 and 22 show examples of the scheduled results obtained byscheduling execution times of transfer devices using the substratetransfer controlling apparatus according to the second embodiment. InFIGS. 21 and 22, the numerals represent substrate numbers, solid linessandwiched by × corresponding to the transfer devices 1 a through 1 cindicate that the transfer devices are in operation, and solid linessandwiched by * corresponding to the processing devices 3 a through 9 dindicate that the processing devices are processing substrates.

FIG. 21 shows the scheduled results obtained immediately after thesubstrate transfer controlling apparatus has started to operate. It canbe seen from FIG. 21 that the transfer devices 1 a through 1 c have alarge allowance at the time immediately after the substrate transfercontrolling apparatus has started to operate.

FIG. 22 shows the scheduled results obtained in a steady state afterelapse of a certain time from the start of operation of the substratetransfer controlling apparatus. In FIG. 22, the quiescent time of eachof the transfer devices is small, and the transfer devices are almostfully in operation. However, with respect to the plating tanks 9 athrough 9 d having a constraint of no waiting time to wait for transferdevice after the processing of substrates, the transfer device startsmoving toward the plating tanks before the processing of substrates isended, receives the substrates immediately after they are processed, andtransfers them to the rough cleaning device 7, as indicated by • in FIG.22.

According to the present invention, as described above, since theexecution times of actions of the transfer devices can be scheduled sothat the time when a final one of the substrates to be processed isfully processed and returned from the substrate processing apparatus ismade earliest, the throughput of the substrate processing apparatus canbe maximized.

The time when a final one of the substrates to be processed is fullyprocessed and returned from the substrate processing apparatus can bemade earliest while satisfying constraints set in relation to the actiontimes of the transfer devices without the need for an awkward advancereview and limitations on expected processing times. Therefore,requirements for the processing of substrates can be met, and thethroughput of the substrate processing apparatus can be maximized.

Even in a situation where the expected processing times of substrateswhile the substrate processing apparatus is in continuous operation cansequentially be obtained in divided forms, the throughput canapproximately be maximized while satisfying limitations on theprocessing of substrates.

Because the number of additional substrates to be scheduled can bepresumed in view of a calculable number of substrates in each schedulingattempt, a computer of relatively low processing capability can performa scheduling process.

Even if actions of transfer devices or the processing of substrates inprocessing devices is delayed behind expected times, it is possible tominimize any effects of the delay on limitations on the processing ofsubstrates and the throughput, and the substrate processing apparatuscan be operated without allowing such effects to remain in the future.

Even if there is a change in conditions with respect to an unintroducedsubstrate, e.g., a cancellation of the processing of the substrate, achange in the expected processing time of the substrate, or a change inthe sequence of introduction of the substrate into the substrateprocessing apparatus, the substrate processing apparatus can be operatedflexibly based on the change in the conditions.

Since a substrate can be transferred to skip an unwanted processingdevice type or types while the substrate processing apparatus is beingcontinuously operated, a plurality of processing device types canselectively be used depending on the purpose of processes performedthereby. Therefore, the throughput of the substrate processing apparatuscan greatly be increased, and the substrate processing apparatus can beoperated flexibly for multi-product small-lot production.

INDUSTRIAL APPLICABILITY

The present invention is suitable for use in a substrate transfercontrolling apparatus for transferring a plurality of substrates in asubstrate processing apparatus such as a semiconductor fabricationapparatus, with transfer devices, successively to a plurality ofprocessing devices for processing the substrates therein, and asubstrate processing apparatus in which the transfer of substrates iscontrolled by such a substrate transfer controlling apparatus.

What is claimed is:
 1. The substrate transferring method of transferringsubstrates with a transfer device between a plurality of processingdevices installed in a substrate processing apparatus, said substratetransferring method characterized by comprising: calculating executiontimes of actions of said transfer device for allowing the time when afinal one of said substrates to be processed is fully processed andreturned from said substrate processing apparatus to be earliest, basedon a predetermined conditional formula including, as parameters, timesrequired for said actions of said transfer device and times required toprocess said substrates in said processing devices, under a constraintrelative to the time to operate said transfer device; and instructingthe corresponding transfer device to perform said actions at thecalculated execution times of said actions of said transfer device. 2.The substrate transferring method according to claim 1 characterized inthat said execution times of said actions of said transfer device arecalculated according to a linear programming process.
 3. The substratetransferring method according to claim 1 characterized by furthercomprising: determining whether or not a solution of said executiontimes of said actions of said transfer device is obtained based on saidconditional formula; and when it is determined that a solution of saidexecution times is not obtained, correcting said conditional formula soas to reduce the average number of substrates which are simultaneouslypresent in said substrate processing apparatus, and retrying calculatingsaid execution times based on the corrected conditional formula.
 4. Thesubstrate transferring method according to claim 1 characterized byfurther comprising: determining whether or not it is necessary to newlycalculate execution times of actions of said transfer device after saidsubstrate processing apparatus has started to operate; when it isdetermined that it is necessary to newly calculate execution times ofactions of said transfer device, determining an assumed time serving asa stating point of calculation of new execution times and a finalsubstrate to be processed in calculating said execution times; and whileholding the result of a past scheduling process prior to said determinedassumed time, calculating new execution times of actions for substratesup to said determined final substrate.
 5. The substrate transferringmethod according to claim 1 characterized by further comprising:acquiring times when said transfer device starts said actions thereof;determining whether or not said acquired times and the execution timesin the result of the past scheduling process are inconsistent with eachother or differ from each other by at least a predetermined range; andwhen it is determined that said acquired times and the execution timesin the result of the past scheduling process are inconsistent with eachother or differ from each other by at least said predetermined range,correcting said execution times of said actions of said transfer devicewhich are not performed at that time.
 6. The substrate transferringmethod according to claim 1 characterized by further comprising:detecting a change in conditions with respect to a substrate expected tobe introduced into said substrate processing apparatus after saidsubstrate processing apparatus has started to operate; and when a changein conditions with respect to said substrate is detected, correctingsaid execution times of said actions of said transfer device on thesubstrate for which a condition is changed and substrates subsequent tosaid substrate for which a condition is changed.
 7. The substratetransferring method according to claim 1 characterized in that when theprocess of at least one processing device in said substrate processingapparatus with respect to at least one substrate is omitted, saidexecution times of said actions of said transfer device are calculatedso as to transfer said at least one substrate to skip said at least oneprocessing device.
 8. A substrate transfer controlling apparatus forcontrolling transfer of substrates with a transfer device between aplurality of processing devices installed in a substrate processingapparatus, said substrate transfer controlling apparatus characterizedby comprising: an input device for inputting times required for actionsof said transfer device and times required to process substrates in saidprocessing devices; a schedule calculator for calculating executiontimes of actions of said transfer device for allowing the time when afinal one of said substrates to be processed is fully processed andreturned from said substrate processing apparatus to be earliest, basedon a predetermined conditional formula including, as parameters, saidtimes inputted with said input device, under a constraint relative tothe time to operate said transfer device; and an action commander forinstructing the corresponding transfer device to perform said actions atsaid execution times of said actions of said transfer device which arecalculated by said schedule calculator.
 9. The substrate transfercontrolling apparatus according to claim 8 characterized in that saidschedule calculator calculates said execution times of said actions ofsaid transfer device according to a linear programming process.
 10. Thesubstrate transfer controlling apparatus according to claim 8characterized by further comprising: a solution judging unit fordetermining whether or not a solution of said execution times of saidactions of said transfer device is obtained by said schedule calculator;and a retrying unit for, when it is determined by said solution judgingunit that a solution of said execution times is not obtained, correctingsaid conditional formula so as to reduce the average number ofsubstrates which are simultaneously present in said substrate processingapparatus, and retrying calculating said execution times by saidschedule calculator.
 11. The substrate transfer controlling apparatusaccording to claim 8 characterized by further comprising: a schedulejudging unit for determining whether or not it is necessary to newlycalculate execution times of actions of said transfer device by saidschedule calculator after said substrate processing apparatus hasstarted to operate; and a calculating condition determiner for, when itis determined by said schedule judging unit that it is necessary tonewly calculate execution times of actions of said transfer device,determining an assumed time serving as a stating point of calculation ofnew execution times and a final substrate to be processed in calculatingsaid execution times by said schedule calculator; wherein said schedulecalculator calculates new execution times of actions for substrates upto said final substrate determined by said calculating conditiondeterminer while holding the result of a past scheduling process priorto said assumed time determined by said calculating conditiondeterminer.
 12. The substrate transfer controlling apparatus accordingto claim 8 characterized by further comprising: an actual timeacquisition unit for acquiring times when said transfer device startssaid actions thereof; a rescheduling judging unit for determiningwhether or not said times acquired by said actual time acquisition unitand the execution times in the result of the past scheduling process areinconsistent with each other or differ from each other by at least apredetermined range; and a corrector for, when it is determined by saidrescheduling judging unit that said acquired times and the executiontimes in the result of the past scheduling process are inconsistent witheach other or differ from each other by at least said predeterminedrange, correcting said execution times of said actions of said transferdevice which are not performed at that time.
 13. The substrate transfercontrolling apparatus according to claim 8 characterized by furthercomprising: a condition change detector for detecting a change inconditions with respect to a substrate expected to be introduced intosaid substrate processing apparatus after said substrate processingapparatus has started to operate; and a corrector for, when a change inconditions with respect to said substrate is detected by said conditionchange detector, correcting said execution times of said actions of saidtransfer device on the substrate for which a condition is changed andsubstrates subsequent to said substrate for which a condition ischanged.
 14. The substrate transfer controlling apparatus according toclaim 8 characterized in that when the process of at least oneprocessing device in said substrate processing apparatus with respect toat least one substrate is omitted, said schedule calculator calculatessaid execution times of said actions of said transfer device so as totransfer said at least one substrate to skip said at least oneprocessing device.
 15. A substrate processing apparatus having aplurality of processing devices for processing substrates whiletransferring said substrates with a transfer device between saidprocessing devices, said substrate processing apparatus characterized bycomprising: an input device for inputting times required for actions ofsaid transfer device and times required to process substrates in saidprocessing devices; a schedule calculator for calculating executiontimes of actions of said transfer device for allowing the time when afinal one of said substrates to be processed is fully processed andreturned from the apparatus to be earliest, based on a predeterminedconditional formula including, as parameters, said times inputted withsaid input device, under a constraint relative to the time to operatesaid transfer device; and an action commander for instructing thecorresponding transfer device to perform said actions at said executiontimes of said actions of said transfer device which are calculated bysaid schedule calculator.
 16. The substrate processing apparatusaccording to claim 15 characterized in that said schedule calculatorcalculates said execution times of said actions of said transfer deviceaccording to a linear programming process.
 17. The substrate processingapparatus according to claim 15 characterized by further comprising: asolution judging unit for determining whether or not a solution of saidexecution times of said actions of said transfer device is obtained bysaid schedule calculator; and a retrying unit for, when it is determinedby said solution judging unit that a solution of said execution times isnot obtained, correcting said conditional formula so as to reduce theaverage number of substrates which are simultaneously present in theapparatus, and retrying calculating said execution times by saidschedule calculator.
 18. The substrate processing apparatus according toclaim 15 characterized by further comprising: a schedule judging unitfor determining whether or not it is necessary to newly calculateexecution times of actions of said transfer device by said schedulecalculator after the apparatus has started to operate; and a calculatingcondition determiner for, when it is determined by said schedule judgingunit that it is necessary to newly calculate execution times of actionsof said transfer device, determining an assumed time serving as astating point of calculation of new execution times and a finalsubstrate to be processed in calculating said execution times by saidschedule calculator; wherein said schedule calculator calculates newexecution times of actions for substrates up to said final substratedetermined by said calculating condition determiner while holding theresult of a past scheduling process prior to said assumed timedetermined by said calculating condition determiner.
 19. The substrateprocessing apparatus according to claim 15 characterized by furthercomprising: an actual time acquisition unit for acquiring times whensaid transfer device starts said actions thereof; a rescheduling judgingunit for determining whether or not said times acquired by said actualtime acquisition unit and the execution times in the result of the pastscheduling process are inconsistent with each other or differ from eachother by at least a predetermined range; and a corrector for, when it isdetermined by said rescheduling judging unit that said acquired timesand the execution times in the result of the past scheduling process areinconsistent with each other or differ from each other by at least saidpredetermined range, correcting said execution times of said actions ofsaid transfer device which are not performed at that time.
 20. Thesubstrate processing apparatus according to claim 15 characterized byfurther comprising: a condition change detector for detecting a changein conditions with respect to a substrate expected to be introduced intothe apparatus after the apparatus has started to operate; and acorrector for, when a change in conditions with respect to saidsubstrate is detected by said condition change detector, correcting saidexecution times of said actions of said transfer device on the substratefor which a condition is changed and substrates subsequent to saidsubstrate for which a condition is changed.
 21. The substrate processingapparatus according to claim 15 characterized in that when the processof at least one processing device in the apparatus with respect to atleast one substrate is omitted, said schedule calculator calculates saidexecution times of said actions of said transfer device so as totransfer said at least one substrate to skip said at least oneprocessing device.